August 2, 2004

Inventing a Way to Walk on Water

By TERESA RIORDAN

Yoav Rosen has received a patent for an apparatus that lets him walk on water. The first such device patented in America was in 1858.

WHEN Yoav Rosen was growing up in Jerusalem in the 1970's, he was obsessed with an act that was said to have been performed only by the likes of Jesus, Buddha and Hindu mystics - walking on water.

Last month, Mr. Rosen received a United States patent (No. 6,764,363) for a device that he says will allow ordinary people to do just that.

Mr. Rosen moved to the United States from Israel three and a half years ago, when his wife took a job as a researcher at the Dana Farber Cancer Institute. But Mr. Rosen, who had been a business and marketing executive
for a software company in Israel, could not find an equivalent job here during the bottom of the dot-com bust.

"So I said to myself, 'Why not start dreaming?' "

Many inventors are afflicted with an overabundance of ideas. Not so Mr. Rosen: "I just had this one idea," he said. "But I've had it since I was 11 years old."

His mother still keeps a picture of a water-walking machine he drew back then. "The design was all wrong," Mr. Rosen said. "There is no way it would have worked."

Of course, neither did Leonardo da Vinci's water-walking device, which he conceived in the late 15th century. His drawing of it is housed at the Biblioteca Ambrosiana in Milan. Da Vinci's invention - if it
had worked - would have operated on a principal similar to cross-country skiing.

In the last 150 years, Americans have patented about 100 water-walking inventions. The first, in 1858, was by H. R. Rowlands, who lived in Boston, not far from where Mr. Rosen resides, in Newton, Mass. Most of the subsequent
patents, Mr. Rosen said, are iterations of that same idea. "Unfortunately," Mr. Rosen observed, "none of them actually work."

Mr. Rosen's device also resembles the 1858 design. His pontoons are made of Styrofoam and plywood, and are tethered together so the user's legs will not spread apart while walking.

"Before you start walking on water you have to stand on water, and that's not an easy thing," Mr. Rosen said. "The water is a living, moving, dynamic thing."

Attached to the back of the pontoons are flaps, which act like paddles, providing propulsion as the legs lift and drop. That idea also echoes the design found in many earlier patents.

But Mr. Rosen's flaps are different from other versions in two significant ways. Rather than being heavier than water, the flaps are buoyant. And they are hinged to the pontoons in a unusual position, which makes
them rotate from 9 o'clock to 12 o'clock. On other water-walkers, he said, the flaps typically rotate from 6 o'clock to 9 o'clock.

"The flap needs to offer maximal resistance from the very beginning of the step, so that the other foot can move forward in real distance terms, and not just relatively to the backward-pushing foot," he said.

Mr. Rosen, who has tested six generations of prototypes, mostly on the Charles River, acknowledges that his version is counterintuitive. "I think that is why this design has eluded hundreds of inventors,"
he said. But, he added, allowing the flaps to rotate quickly enough means a person using the contraption can walk at a normal gait.

Earlier this year, Mr. Rosen started selling a related vessel, a standing paddle boat for sports fishermen, which is carried by about 20 kayak and canoe stores, mostly in the Northeast.

He calls it the W boat, for the shape of the wake that it produces.

"It's basically a one-man show," he said. "I have drowned a lot of money in this venture."

His Web site, www.wavewalk.com, features a section on his water-walking invention, but it could be some time before water-walking becomes a common sight.

"I haven't brought it to market for a very simple reason: distribution channels," Mr. Rosen said. "What store would sell it? It doesn't fit into an existing paradigm for sports."